FIG. 1 depicts a conventional method 10 for fabricating a magnetoresistive sensor in magnetic recording technology applications. FIGS. 2-3 depict a conventional transducer 50 during fabrication using the method 10. The method 10 typically commences after a conventional magnetoresistive, or MR, stack has been deposited. The conventional magnetoresistive stack typically includes an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. In addition, seed and/or capping layers may be used. The pinned layer may be a synthetic antiferromagnetic (SAF) layer including magnetically coupled ferromagnetic layers separated by a nonmagnetic spacer layer. The nonmagnetic spacer layer may be a conductive layer for a giant magnetoresistive sensor or an insulator for a tunneling magnetoresistive sensor. The free layer is ferromagnetic and has a magnetization that is free to change in response to an external magnetic field, for example from a media.
The conventional method 10 commences providing a conventional organic mask, via step 12. The conventional organic mask provided in step 12 is typically a photoresist mask. The conventional photoresist mask covers the region from which the conventional magnetoresistive sensor is to be formed, as well as the field region of the transducer 50. However, part of the device region adjoining the magnetoresistive sensor is left uncovered. The magnetoresistive sensor is defined, via step 14. Step 14 typically includes ion milling the transducer 50. Thus, the portion of the magnetoresistive stack exposed by the conventional photoresist mask is removed. FIG. 2 depicts air-bearing surface (ABS) and plan views of a conventional, magnetic recording read transducer 50 after step 14 is completed. For clarity, FIG. 2 is not drawn to scale and only certain structures are depicted. The conventional transducer 50 magnetoresistive layers 54 which have been defined to provide a conventional magnetoresistive sensor 56. Because the regions adjacent to the conventional magnetoresistive sensor 56 were exposed, the conventional magnetoresistive sensor 56 has been formed. Also shown is conventional photoresist mask 58 which has a first portion 62 covering the magnetoresistive sensor 56 and remaining portions 60 that cover the remaining device and field regions. The photoresist mask 58 used is typically very thick. For example, the photoresist mask may be on the order of one hundred sixty nanometers or higher.
The hard bias material(s) are deposited, via step 16. In addition, seed and/or capping layers may be provided in step 16. The hard bias material(s) and other layers are deposited while the conventional photoresist mask 58 is in place. A lift-off of the conventional photoresist mask 58 is then performed, via step 18. FIG. 3 depicts the conventional transducer 50 after step 18 is performed. Thus, the hard bias material(s) 64 are shown. The hard bias material(s) to the left are denoted 64L, while the hard bias material(s) to the right of the magnetoresistive sensor 56 are denoted 64R. Fabrication of the conventional transducer 50 may be completed.
Although the conventional method 10 allows the conventional transducer 50 to be fabricated, there are several drawbacks. In particular, there may be asymmetries in the conventional transducer 50. As can be seen in FIGS. 2-3, the conventional magnetoresistive sensor 56 is asymmetric. These asymmetries may become significant at smaller track widths, for example thirty to forty nanometers or less. In particular, the junction angles θ and φ may differ significantly. Further, multiple transducers 50 are typically fabricated from a single wafer. There may also be variations in the junction angles between transducers 50 fabricated on the same wafer. Transducers closer to the center may have a smaller variation in junction angles than transducer 50 closer to the edge. For conventional transducers 50, the average difference between the left junction angle φ and the right junction angle θ may be seven or more degrees. Further, as can be seen in FIG. 3, the hard bias 64L and 64R are asymmetric. Again, this asymmetry may vary across a wafer. These variations between conventional transducers 50 may adversely affect performance and/or yield.
Accordingly, what is needed is a system and method for improving the fabrication of a magnetic recording read transducer.